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Anthracene Based Conjugated Polymers: Correlation between π−π-Stacking Ability, Photophysical Properties, Charge Carrier Mobility, and Photovoltaic P…
2010
This article reports on the synthesis, characterization and properties of a series of anthracene−containing poly(p-phenylene-ethynylene)-alt-poly(p-phenylene-vinylene)s (PPE−PPV) copolymers with general constitutional unit (Ph−C≡C−Anthr−C≡C−Ph−CH═CH−Ph−CH═CH−)n denoted AnE-PV. Solely linear (AnE-PVaa, -ad, -ae) and solely branched (AnE-PVbb) as well as mixed linear and branched (AnE-PVab, -ac, -ba, -cc) alkoxy side chains were grafted to the backbone in order to tune the π−π-stacking ability of the materials. It has been possible to establish a correlation between π−π-stacking ability, absorptive behavior, charge carrier mobility, solar cell active layer nanoscale morphology and resulting p…
Well-Defined Multi-Amino-Functional and Stimuli-Responsive Poly(propylene oxide) by Crown Ether Assisted Anionic Ring-Opening Polymerization
2017
Multi-amino-functional poly(propylene oxide) (PPO) copolymers were synthesized by the anionic ring-opening copolymerization (AROP) of N,N-diethyl glycidyl amine (DEGA) and propylene oxide (PO). A solvent free synthesis route using potassium counterions and crown ether for the AROP enabled controlled (co)polymerization with full conversion. The strategy provided access to PPO-b-PDEGA block copolymers, statistical PPO-co-PDEGA copolymers, and, for the first time, PDEGA homopolymer. Molecular weights in the range of 1400 to 4200 g/mol (Mn) and dispersities (Mw/Mn) below 1.1 were obtained. Both the kinetics and resulting microstructure of the statistical copolymerization were investigated by in…
Solution and fluorous phase synthesis of β,β-difluorinated 1-amino-1-cyclopentane carboxylic acid derivatives
2008
An efficient protocol for the preparation of β,β-difluorinated 1-amino-1-cyclopentane carboxylic acid derivatives was developed. 2,2-Difluro-4-phenyl-3-butenoic acid 6 was used as substrate for the preparation of the starting vinyl difluoro imino esters 8. The key steps of this methodology rely on the chemo- and diastereoselective addition of allylzinc bromides over the iminic functionality of 8 and subsequent RCM reaction. This synthetic sequence was successfully applied to fluorous synthesis.
Synthesis of poly(disulfide)s with narrow molecular weight distributions via lactone ring-opening polymerization
2020
We report the first example of controlled polymerization of poly(disulfide)s with narrow molecular weight distributions. 1,4,5-oxadithiepan-2-one (OTP), a disulfide-containing 7-membered ring lactone, was polymerized by using the diphenylphosphate (DPP) catalyzed lactone ring-opening polymerization method. The polymerization proceeded in a living manner, and the resulting polymers displayed very narrow polydispersity index (PDI) values below 1.1 and excellent backbone degradability responding to reducing conditions and UV irradiation.
Alkyl Complexes of Group 4 Metals Containing a Tridentate-Linked Amido−Cyclopentadienyl Ligand: Synthesis, Structure, and Reactivity Including Ethyl…
1998
A series of group 4 metal complexes M(η5:η1:η1-C5Me4SiMe2NCH2CH2X)R2 (M = Ti; R = Me, CH2Ph; M = Zr, Hf; R = Me, Et, nPr, nBu, CH2Ph, CH2SiMe3, Ph) containing the tridentate-linked amido−tetramethy...
Chiral Lanthanocene Derivatives Containing Two Linked Amido−Cyclopentadienyl Ligands: Heterobimetallic Structure and Lactone Polymerization Activity
1997
Reaction of 2 equiv of dilithium amido−cyclopentadienide Li2(C5R4SiMe2NCH2CH2X) (C5R4 = C5Me4, C5H3tBu; X = OMe, NMe2) with anhydrous LnCl3 (Ln = Y, Lu) gave C2-symmetric complexes of the type Li[Ln(η5:η1-C5R4SiMe2NCH2CH2X)2] containing a heterobimetallic core. The molecular structure of Li[Y(η5:η1-C5Me4SiMe2NCH2CH2OMe)2] was determined by single-crystal X-ray structural analysis, which showed it to exhibit both a pseudotetrahedral yttrium as well as a tetrahedral lithium center. In accordance with a formal 20-electron configuration at the rare earth metal center Ln, the amido-nitrogen atoms are shown to be pyramidalized. In the case of Li[Y(η5:η1-C5H3tBuSiMe2NCH2CH2X)2], mixtures of the tw…
Chloroplastic glutamine synthetase from Brassica napus.
1993
Long-chain branched ROMP polymers
2009
This article describes the construction of branched ROMP-polymer architectures via polycondensation of ABn-type macromonomers. For this convergent strategy, a polymer was synthesized that carries several hydroxyl-groups along the polymer chain and one carboxylic acid group at the chain end. An esterification reaction between these functional groups yielded long-chain branched polymers. The polymers were analyzed by NMR and SEC to monitor the condensation reaction. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009
Persistent photovoltage in methylammonium lead iodide perovskite solar cells
2014
Open circuit voltage decay measurements are performed on methylammonium lead iodide (CH3NH3PbI3) perovskite solar cells to investigate the charge carrier recombination dynamics. The measurements are compared to the two reference polymer-fullerene bulk heterojunction solar cells based on P3HT:PC60BM and PTB7:PC70BM blends. In the perovskite devices, two very different time domains of the voltage decay are found, with a first drop on a short time scale that is similar to the organic solar cells. However, two major differences are also observed. 65-70% of the maximum photovoltage persists on much longer timescales, and the recombination dynamics are dependent on the illumination intensity.